BOOK REVIEW

“Screen early, screen often” has become the hallowed mantra in our medicalized culture. Screening healthy people for signs of sickness is increasingly promoted to prevent disease and save lives. The list of tests given to healthy people at younger and younger ages is prodigious: whole body scans, cholesterol tests, PSA tests, mammograms, colonoscopy, depression and ADHD tests, and the list is growing.

But is all this screening good for our health? Is it actually saving our lives? Or is it putting us in jeopardy?

In Seeking Sickness: Medical Screening and the Misguided Hunt for Disease, author Alan Cassels tackles this touchy topic, looking at it test by test. His overarching message is that modern medicine has “overpromised” with claims that screening will save our lives. He contends that with the lack of hard evidence on benefits, the evidence of harm from by such screening, as well as the multi-billion dollar interests at stake, we should approach this kind of screening with great precaution.

Cassels is a drug policy researcher in British Columbia and has probed the topic of medicalization of healthy people—and the money behind it—before. In the book Selling Sickness: How the World’s Pharmaceutical Companies are turning is all into Patients, Cassels and co-author Ray Moynihan critiqued how drugs companies are behind the push to define new illnesses for which they—miraculously—have just the right pill.

Note an important distinction: Seeking Sickness is mainly about screening tests for healthy people, not diagnostic tests for people who have a significant risk and/or symptoms of a particular disease.

The book is clearly organized with each chapter focused on a specific type of test. He addresses the dangers of the tests (e.g., the radiation from mammograms, infections from prostate biopsies) and the tests’ accuracy (how many false positives does it generate)? And he discusses the dangers of the “downstream” effects of a positive result. That is: What further tests and treatments are you going to be prescribed as a result of this test? And might those treatments be worse than the disease or condition itself?

Several of the tests are of particular interest to women.

In the chapter on mammography Cassels argues that statistics about screening's benefits can be very misleading. Some organizations, such as the Canadian Breast Cancer Foundation have said that early mammography screening can reduce deaths from breast cancer by 25 to 35 per cent among women who start screening from age 40. Cassels dissects that claim, noting that, “25 to 35 per cent amounts, in real numbers, to this: about 1 in 2,100 women over 11 years has had her life saved by being screened.”

Cassels says we should also know the statistics about how women’s lives are worsened by screening.

He quotes the Canadian Task Force on Preventative Health Care, when it put forward a new set of breast cancer screening recommendations in 2011, that screening that many women for that long would result “in about 690 women having a false-positive result on a mammogram, leading to unnecessary follow-up testing, and 75 women having an unnecessary biopsy on their breast.”

Pap tests for cervical cancer are one of the most common screening tests given to healthy women, and Cassels argues that more targeted testing is needed. While wealthier women in the developed world tend to be adequately screened, Cassels notes that this is not the case for poor women, and those in the developing world. “More, not less, cervical-cancer screening is actually needed in the poorest parts of the world," he writes.

With the example of the Pap, Cassels proposes that the “Inverse Screening Law” is alive and well in modern medical practice. “Much energy and money is spent on pushing useful screening tests beyond the need for them rather than focusing them on the populations who are probably at the highest risk and who would get the most benefit from them.”

Seeking Sickness carries a timely message, as it was published months before the Canadian Task Force on Preventive Health Care in Canada recommended not screening low risk (i.e., not sexually active) women, and starting screening at an older age (25) and ending it by age 70.

Cassels will likely raise hackles when he says that some cancers found by screening are being unnecessarily treated. Men 65 years old have a 50 to 65 per cent chance of having prostate cancer, yet less than 3 per cent of men will die from it. Most prostate cancers are slow-growing and the men with it will likely die from something else in old age. Men with prostate cancers found by PSA testing don’t live longer than men whose prostate cancers are discovered by other means. These facts led to the US Preventative Services Task Force’ 2011 recommendation that the PSA NOT be done on healthy men as it was resulting in unnecessary treatment.

Why has screening of healthy people become such a widespread phenomenon?

Cassels follows the money on that one. Using the example of bone-density testing, and citing the work ofDr. Gillian Sanson, author of The Myth of Osteoporosis, he looks at the huge push to “marketize” osteoporosis, and how the push to have women tested was driven by the drug companies marketing bisphosphonates.